The present invention relates to a communication apparatus, typically a facsimile apparatus. More specifically, the invention relates to a communication apparatus which has an extension-line connector to be connected to a private branch exchange and an external-line connector to be connected to external lines, and which is capable of communicating separately with extension station and external station.
There have conventionally been proposed facsimile apparatuses which are provided with two sets of communication control units and an extension-line connector and an external-line connector so as to be able to separately communicate with an external station and extension station. Hereinafter, a brief description will be given of such a facsimile apparatus.
FIG. 1 is a block diagram of such a facsimile apparatus. In the drawing, thick arrows indicate a flow of data, while thin arrows indicate a flow of a control signal.
A scanner 1 and a printer 2 are connected to a data control unit 3, which is connected to a bus 4. Two sets of communication control units 5A, 5B are connected to an NCU 8 via a distributor 7, and also to the bus 4.
The NCU 8 is provided with an extension-line connector 15 to be connected to a PBX (private branch exchange) 19 and an external-line connector 16 to be connected to external lines. The NCU 8 is adapted to send a call via the external-line connector 16 usually.
The communication control units 5A and 5B are respectively provided with buffers 12A and 12B, data companders 13A and 13B, and buffers 14A and 14B, and are adapted to compress image information to be transmitted which is transferred from the scanner 1 or a large-capacity memory 9 or expand image information received via the NCU 8 and the distributor 7, in accordance with a prescribed method.
The large-capacity memory 9 for storing image information to be transmitted or image information received and a system control unit 10 for controlling the facsimile apparatus are also connected to the bus 4.
The system control unit 10 has an abbreviated-dialing-number storage means 10A in which abbreviated dialing numbers for use in calling an external station via the external-line connector 16 are registered.
Connected to the system control unit 10 is a panel 11 which is provided with an extension button 11A for accessing the PBX 19 by selecting the extension-line connector 15, abbreviated-dialing buttons 11B for sending a call to an external station using an abbreviated dialing number, a ten-key pad 11C for dialing, and other various operating means, various display units, etc.
FIG. 2 shows the operation of the facsimile apparatus having the above-described arrangement in the case where an attempt is made to communicate with an external station by operating one of the abbreviated-dialing buttons 11B when a communication is already being carried out with another external station via the external-line connector 16.
In FIG. 2, if it is first judged in Step S1 that one of the abbreviated-dialing buttons llB has been depressed, it is judged in Step S2 whether or not a communication is already going with an external station via the external-line connector 16.
If a communication is being conducted with no external stations, the external-line connector 16 is selected in Step S3, a dialing number which has been selected by the abbreviated-dialing button llB is read out from the abbreviated-dialing-number storage means 10A in Step S5, and a call is initiated.
Then, in Step S6, either of the communication control units 5A, 5B which is not being used for any communication is selected, and is connected to the call-initiated external station.
If it is judged in Step S2 that a communication is going with an external station, it is judged in Step S7 whether or not a predetermined time has elapsed. After the lapse of that time, the processing returns to Step S2, and it is again judged whether or not a communication is being made with an external station. If a communication is not being made with any external stations, the external-line connector 16 is selected and a call is initiated.
However, the above-described prior art apparatus has the following problem. If an attempt is made to communicate with an external station when a communication is already going with another external station via the external-line connector 16, the attempt is placed in a waiting state until the communication started earlier is completed.